The search for the ideal material for restorative dentistry has recently focused on the development and analysis of dentin bonding agents that bond to conditioned dentin and that are hydrolytically stable. Conflicting and quite variable results have been reported on the bond strength of these agents to conditioned dentin. The overall objective of this proposal is to develop a dentinal bonding agent-luting agent system for enhanced adhesion of resin-based composites, conservative ceramic inlays, and ceramic shell crowns. The major focus of this project will be to produce a bonding agent that is as technique insensitive as possible. In addition, the bonding agent must also be compatible with the experimental composites currently under development and clinical evaluation at the University of Florida through NIH/NIDR Grant No. DE09292. The bonding ability will be based on resin infiltration of the bonding agent into a demineralized collagen film on the conditioned dentinal surface. To meet this objective, the following aims are proposed: 1) Test the hypothesis that amino acids, such as glycine and proline, can be used efficiently as conditioners for dentin, even if the dentin is contaminated with saliva. Since both glycine and proline are the main components of collage, we will further determine whether certain treatment conditions with these two amino acids cause collagen degradation. 2) Identify the most promising conditioning and priming aspects of collagen regarding resin infiltration, and test the hypothesis that a primer consisting of KAl(SO4)2.12H2O and ammoniac is as efficient as presently used primers. 3) Test the hypothesis that a polyacrylic acid, to which terminal and/or pendant amino acid groups and methylmethacrylate groups have been attached, enhances the infiltration ability of a primer into collagen. 4) Test the hypothesis that residuals of conditioners, moisture and Ca- and P-ions, present in the collagen web after etching, significantly affect the polymerization degree of the resin within the collagen network. By maximizing polymerization, we believe that maximal bond strength wil be achieved. 5) Test the hypothesis that the large variations in bond strength values are mainly due to defects induced during the bonding procedure. 6) Test the hypothesis that in vitro marginal leakage, determined with a diffusion marker, is related to the collagen film and the resin infiltration depth into that film. 7) In an animal study, test the hypothesis that the best materials identified in the previous aims will not cause any significant pulp damage despite aggressive etching of dentin. 8) Assuming that the results of Aim 7 are favorable, conduct a one-year clinical evaluation of the most promising product. The objective of that study will be to test the hypothesis that it is possible to achieve an almost 100% success rate regarding both retention and pulpal response with the total-etch technique.